The fragile X (FRAXA) syndrome is the most common form of inherited mental retardation in males. Its peculiar pattern of inheritance results from the parent of origin-specific expansion of a CGG-repeat within the FMR1 gene on the X chromosome. In patients, gene function is abolished by hypermethylation of the promoter and the massively expanded repeat. We have developed a methylation-sensitive polymerase chain reaction (MS-PCR) strategy that combines repeat-length and methylation analysis of the CGG-repeat and the promoters of the FMR1 and XIST genes. The allelic methylation of the latter opposes that of the FMR promoter and serves as an internal control and standard for semiquantitative analyses. This system enables the delineation of 11 distinct patterns encountered in nonaffected, carrier, and affected males and females. We have evaluated our system on well-defined samples with different FMR1 mutations and have used it for the diagnostic evaluation of 253 male and 80 female probands. In the male group, we have identified five full mutations, and three gray-zone and premutation alleles with 54, 55, and 62 repeats, respectively. The female group consists of 33 normal homozygote and 41 heterozygote individuals, two of whom harbor a gray-zone allele with 47 repeats, none with a premutation, and six with a full mutation. Our MS-PCR approach allows the currently most comprehensive diagnostic evaluation of the FRAXA syndrome in a cost- and time-efficient fashion. In addition, it is a valuable tool for the analysis of clonality and skewing phenomena in females.
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http://dx.doi.org/10.1007/s004390100519 | DOI Listing |
J Neurodev Disord
January 2025
Graduate Neuroscience Program, University of California, Riverside, CA, USA.
Background: Fragile X syndrome (FXS) is a leading known genetic cause of intellectual disability and autism spectrum disorders (ASD)-associated behaviors. A consistent and debilitating phenotype of FXS is auditory hypersensitivity that may lead to delayed language and high anxiety. Consistent with findings in FXS human studies, the mouse model of FXS, the Fmr1 knock out (KO) mouse, shows auditory hypersensitivity and temporal processing deficits.
View Article and Find Full Text PDFFragile X Syndrome (FXS) is characterized by intellectual impairment caused by CGG repeat expansion in the FMR1 gene. When repeats exceed 200, they induce DNA methylation of the promoter and the repeat region, resulting in transcriptional silencing of the FMR1 gene and the subsequent loss of FMRP protein. In the past decade or so, research has focused on the role of FMRP as an RNA-binding protein involved in translation inhibition in the brain in FXS model mice, particularly by slowing or stalling ribosome translocation on mRNA.
View Article and Find Full Text PDFProg Neuropsychopharmacol Biol Psychiatry
December 2024
Dept. Science, Roma Tre University, Rome, Italy; Neuroendocrinology, Metabolism and Neuropharmacology Unit, IRCCS Fondazione Santa Lucia, Rome, Italy. Electronic address:
β-Caryophyllene (BCP) is a naturally occurring sesquiterpene found in numerous plant species, including Cannabis sativa. BCP has shown a high safety profile and a wide range of biological functions, including beneficial effects in neurodegenerative and inflammatory diseases. Here, we used behavioral, pharmacological, and in-silico docking analyses to investigate the effects and mechanism of action of BCP in Fragile X Syndrome (FXS), the most common inherited cause of Autism Spectrum Disorder (ASD) and intellectual disability.
View Article and Find Full Text PDFJ Med Chem
December 2024
Medicines Discovery Institute, School of Biosciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K.
LIMKs are serine/threonine and tyrosine kinases responsible for controlling cytoskeletal dynamics as key regulators of actin stability, ensuring synaptic health through normal synaptic bouton structure and function. However, LIMK1 overactivation results in abnormal dendritic synaptic development that characterizes the pathogenesis of Fragile X Syndrome (FXS). As a result, the development of LIMK inhibitors represents an emerging disease-modifying therapeutic approach for FXS.
View Article and Find Full Text PDFEffectively addressing ethical issues in precision medicine research in Africa requires a holistic social contract that integrates biomedical knowledge with local cultural values and Indigenous knowledge systems. Drawing on African epistemologies such as ubuntu and ujamaa and on our collective experiences in genomics and big data research for sickle cell disease, hearing impairment, and fragile X syndrome and the project Public Understanding of Big Data in Genomics Medicine in Africa, we envision a transformative shift in health research data governance in Africa that could help create a sense of shared responsibility between all stakeholders in genomics and data-driven health research in Africa. This shift includes proposing a social contract for genomics and data science in health research that is grounded in African communitarianism such as solidarity, shared decision-making, and reciprocity.
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